<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>标记选择器</title>
		<script src="js/jquery-3.3.1.min.js" type="text/javascript" charset="utf-8"></script>
	</head>
	<body>
		<p class="c1">p_1</p>
		<p class="c1" id="p2">p_2</p>
		<p class="c2" id="p3">p_3</p>
	</body>
</html>
<script type="text/javascript">
	$("p").css("border","5px solid red");
</script>
